Protecting the value of media content is among the biggest challenges of media content delivery. Without proper protection, content owners, content providers, and service providers may be reluctant to release their valuable media content. In the past, digital rights management has been widely used for content protection. Valuable media content is encrypted in scrambled form, which prevents unauthorized access to the media content. Only those with the proper rights to the media content could decrypt and access the content.
However, digital rights management is a passive content protection scheme and only protects the content very well when the media content is in scrambled form. When the media content is decrypted and in its clear form, the protection is gone. While in the clear form, the media content may be freely copied and distributed. Thus a more active content protection technique is needed. The active content protection technique may be used in additional to digital rights management.